Updated: Oct 15, 2021
Is Squash Self Pollinating?
For squash to pollinate, it is necessary to have a male and female flower. The male and female flowers are on one vine, but pollinators will need to carry pollen from male flowers to female flowers. If this does not occur, the little squash will turn yellow and fall from the vine. If your pollination is successful, you would see your little squash enlarging as the days pass.
Pollinating Squash Flowers/Squash Pollination by Hand
Here is a guide to pollinating kabocha squash flowers. In the picture below, you can see the male flower, which has no budding fruit. The female flower has a budding fruit at the base of the blossom, which is the ovary. Normally bees will carry the pollen between the male and female flowers. Bees will carry the pollen from the anther or male flower to the female flower or stigma. When the pollen goes onto the stigma, it pollinates that flower. After pollination, the blossom will fall off, and the fruit or ovary will start to enlarge, and you will have a beautiful, delicious squash growing. If the female flower is not pollinated, then the blossom will fall off, and the fruit or ovary will turn yellow and start to die and fall off the vine.
I want to share with you how I hand pollinate if I have no bees working in my area. First, after the male flower has opened up, I'll check to see if there is pollen on the anther. If I can see pollen on the anther, I will break the flower off. Then I will tear the petal away from the base and go to an open female flower and rub the anther on the stigma. This will allow the pollen to stick to the stigma and pollinate the flower. This method works well for me. The picture is difficult to see, but I have taken the male flower(anther) and rubbed it on the female flower(stigma).
Another method you can try would be using a small paintbrush. Just use the bristles to take the pollen off the anther and then brush the pollen onto the stigma. I have never tried this method, so I don't actually know how well it works.
To help bring more pollinators to your yard, plant a very diverse garden. You want many different types of flowers, and you'll also want many different flowering times. Plant something that flowers early in the season and late in the season. When you plant that way, you'll have pollen for bees from spring to fall.
Hopefully, I have a new kabocha Squash growing now. I will update as everything happens.
The male flower is lying inside the female flower
Here is a male kabocha squash with the anther exposed and labeled.
Here is the female kabocha squash flower showing the stigma.
Here is the female kabocha squash flower showing the ovary.
This example is a squash that has not been pollinated. You can see that it is starting to lighten in color and will turn yellow soon.
After the squash has been pollinated you can see that it is turning darker green.